This invention relates to a dynamic tension control apparatus and tensioning method for an aero-mechanical conveyor. Aero-mechanical conveyors are often used to convey powders and other particulate matter by entraining the particulate matter in a moving airstream. Such conveyors typically include an endless wire rope assembly upon which dividers are fastened and used for carrying the particulate matter. The rope assembly is typically carried on drive and driven pulleys enclosed within infeed, corner, and discharge housings in various configurations. The housings are interconnected by two tubes through which the rope assembly travels as it moves around the drive and driven pulleys. As the conveyor operates, forces are exerted on the rope assembly that can cause the rope assembly to stretch. Such forces are created by normal wear on the conveyor, the weight of the material being conveyed along the rope assembly, and similar other factors. The rope assembly can stretch to the point that a conventional tensioning device cannot exert adequate tension on the rope.
While prior art manual tension adjusting mechanisms exist for moving the head and tail pulley assemblies relative to each other to maintain the correct amount of tension on the rope assembly, such mechanisms are often inadequate. For example, some traditional prior art tension adjusting mechanisms rely on clamps which fasten the semi-circular housings to the tubes. Tension on the rope assembly is adjusted by loosening the bolts that hold the clamps in place and sliding one or both of the housings inwardly or outwardly relative to the tubes. Another prior art method of adjusting the tension on the rope assembly involves moving the drive or driven pulley together with the housing. Regardless of which prior art method is employed, adjusting the tension by moving the housings relative to the conveyor tubes is a manual operation. In addition, the discharge end of the equipment is frequently inaccessible, making access to the tube-joining clamps challenging, and according to each method, the clamps have to be slackened and re-tightened. Furthermore, once the tension has been adjusted, there is no guarantee that the tubes and the connecting spigots leading to the housings will be properly aligned, which makes jamming a possible cause of failure.
The invention of the present application overcomes the problems inherent to the prior art described above by providing a tension control apparatus for use on an aero-mechanical conveyor that adjusts tension by moving the housings and pulley assemblies automatically and without requiring any significant manual intervention. The tension control apparatus of the present invention uses a constant load device such as a pneumatic cylinder that applies a pre-selected amount of tension on the rope assembly. In addition, the present invention can include a visual or electronic indication of when the tension control apparatus must be reset due to excessive rope stretch.